Telephone system



Jan. 12, 1943. 1 OD SHEPHERD y 2,307,964

TELEPHONE SYSTEM Filed June 19,v 1941 6 Sheets-Sheet l )VEA/70H J. 0D SHEPHERD AHORA/Ey Jan. 12, 1943.

JQoD SHEPHERD TELEPHONE SYSTEM Filed June 19, 1941 6 Sheets-Sheet 2 WEA/ro@ J. O'D. SHEPHERD ATTORNEY Jan. 12, 1943. J. O'D SHEPHERD 2,307,964

' TELEPHONE SYSTEM Filed June 19, 1941 6 Sheets-Sheet 5 WIIHP -illw- A TTORNEV Jan. 12, 1943. oD SHEPHERD 2,307,964

TELEPHONE SYSTEM Filed June 19, 1.941 Y 6 Sheets-Sheet 6 Il" 'i V1 RELAY RELAY CHAIN PULSE ANO RING CONI' 6 OUN TINE /NVENTOR J. 0'0. SHEPHERD @rmi/TW;

Patented Jan. 12, 1943 UNITED STATES PATENT OFFICE.

TELEPHONE SYSTEM Judson OD Shepherd, Atlanta, Ga.

Application June 19, 1941, Serial No. 398,697

13 Claims.

This invention relates to switching systems and devices and more particularly to such systems and devices when used in the establishment of telephone connections.

An object is to simplify the automatic equipment and circuit facilities for establishing telephone connections between subscribers lines and for hunting for idle trunking connections in telephone systems.

Heretofore switching devices have been provided in which connections between subscribers lines were established by contacts selected and operated by code bars shifted in combinations in accordance with digits dialed.

The present invention relates to such switches having code bars and in which an incoming line may be connected to any one of a plurality of outgoing lines by the operation of combinations of code bars, and a feature thereof is an arrangement of a plurality of switches with one line in each switch having access to a plurality of lines terminating therein and in which said plurality of lines are multipled across from switch to switch. For example, this feature may be applied to an arrangement whereby connections are to be established between subscribers lines where such subscribers lines are multipled across the switches, some serving as line iinders and others as selector connectors with an individual line or link connecting a line finder and a selector connector. By this arrangement the calling line may be connected through an idle line finder and an associated link leading to a selector connector by operation of combinations of code bars, in

said line finder, and connections may then be made between this link and a called line by the operation of code bar combinations in this selector connector.

It is another feature of the present invention whereby connections may be established through a switch such as a selector connector from a link to an idle outgoing trunk by means of certain operations of the code bars. The arrangement is such that one set of code bars may be operated in combinations to select a corresponding group of trunks and whereby said selecting operations cause the switch to be automatically operated to select other code bars to cause them to complete a connection between a link and an idle trunk directly in the selected group. This arrangement therefore enables the code bar switches in accordance with the applicants invention to be employed to establish a connection to an idle trunk without testing the busy trunks individually.

It is another feature of the invention to provide a switch structure of this type in which the circuit-making contacts consist of individual groups of contact springs comprising two or more sets of contact springs, each set consisting of two springs adapted for operation to connect with each other. These groups are arranged in two separate parallel rows of groups on opposite sides of the code bars, each group of contact springs being controlled by actuators that may enter slots in the bars when said bars are selected and shifted in combinations and a retention means in the form of a bar for each row of actuators. The arrangement may be such that the code bars are provided with slots on opposite sides and selected in combinations by individual magnets to align slots in front of a particular actuator and then the retention bars are released by magnets to permit the selected actuator to enter the aligned slots and thereby operate the associated group of contact springs to close the desired connections. By this construction, the actuators are normally prevented from engaging the bars to permit the free operation thereof to select the desired group of contacts for the subsequent operation thereof by the associated actuator when the retention bars are released.

The applicants invention has been illustrated in the accompanying drawings in which Figures 1 to 11 show details of a switch structure to which the applicants invention has been applied. Figs. 12 and 13 show a circuit arrangement employing this switch as a line iinder and as a selector-connector in a telephone system. Of Figs. 1 to 11:

Figure 1 shows a side View of a code bar switch;

Fig. 2 shows a bottom view of this switch;

Figs. 3 to 7 show cross-sections of the switch shown in Fig. 1 taken on the lines indicated with the numerals 3 3, 4 4, 5 5, 6 6 and 1 1, respectively;

Fig. 8 is similar to Fig. 5 except that it shows one of the set of contacts in operate position;

Fig. 9 is a fragmenary perspective View of a so-called select magnet, its operating mechanism and one of the code bars;

Fig. 10 shows a fragmentary perspective view of a so-called operating magnet and its various operating details, part of a code bar and a set of select springs;

While Fig. 1l shows various off-normal and operating and code bars in detail indicating the arrangement of slots in the sides of the bars for the selection of particular select springs.

Referring now to Figs. l to l1 showing an individual switch structure, Fig. 1 shows that the structure may consist of a base plate |69 and a cover lill attached thereto and inside of which the details of the switch are located with the exception of the ends of terminals such as shown at M2 and IQZA that protrude outside of the structure and to which circuit connections may be made in multiple to other switches. To the base plate |66 may be attached a carriage plate |03 and to this plate are mounted a series of magnets for controlling the series of code and operating bars indicated as a whole at |64. In the central position of the switch are located four magnets ISE in a row which may be termed tens select magnets and at the left of these are located in a row four magnets H35 which may be termed units select magnets. On the lefthand side of the units magnets is located a socalled operating magnet Il and on the righthand side of the tens select magnets is located another operating magnet |28. On the right of thisv operating magnet m8 is located a so-called trunk operating magnet |09 and on the lefthand side vof the operating magnet iti? is located a release magnet H. The code and operating bars H34 are journaled in the side channel plates and I|2 and these bars are shiftable longitudinally between the plates and ||2 and may be restored to normal positions by means of restoring springs 3 as shown in Figs. 1 and 3. These bars also control various kinds of offnormal springs as shown in Figs. 1 and 4 for purposes to be described hereinafter. At opposing sides of the bars IM are located sets of select springs such as are indicated at H43, Fig. 1 in ygeneral and also shown in side views such as Figs. 5, 6, 7 and 8 in particular. Each one of these sets of select springs referring particularly to Fig. 5, for example, consists of a series of fixed and movable springs for making three separate electrical connections. The movable springs are controlled by an operating spring H5 which has an extension U6 that may register with slots in the bars when shifted to establish connections between the select springs, as will be described hereinafter. These extensions IIS are guided in transverse slots in longitudinally extending guide plates ||1 connected at opposite ends to supports H8 connected to the plate |23.

Referring particularly to Fig. 11, the code bars and operating bars |84 may be arranged as shown in this gure with four units code bars |20, four tens code bars 12|, a units off-normal bar |22 and a tens olf-normal bar |23 and a latch bar |215. The slots on opposite sides of the tens and units bars may be arranged as shown in this figure to provide for the selection of any one of one hundred sets of select springs by shifting the units bars and tens bars in different combinations to align slots to permit an eXtension ||6 to enter into said slots, to actuate the associated select springs. The one hundred sets of select springs may be arranged, either as line connecting springs or as trunk connecting springs in any desired combination. At the left-hand end of the tens code bars |2| there is arranged a special series of slots |25 for selecting one out o-f ten special select springs employed, as will hereinafter be described and for trunk group selecting operations. It will be noted that the tens and units code bars are provided with rec-.

tangular slots in the center through which project members which are operated upon by the tens and units magnets to shift the bars. Each member operates on a corresponding bar and is actuated by the armature of a corresponding tens or units magnet to shift the code bars towards the right looking at Fig. 1. Other slots in the bare are for the purpose of permitting the members from the various magnets to pass freely through these slots to engage their corresponding bars as the bars are shown placed on top of each other. Fig. 9 illustrates a tens or units magnet with its armature |28 and its extension |21 passing freely through a slot in one code bar to enter a slot in another code bar for the shifting of this latter code bar. It should be observed in Fig. 11 that the units off-normal bar |22 and tens off-normal bar |23 are also provided with slots for operation of these bars simultaneously with the operation of any of the extensions such as |21 of any of the corresponding tens or units magnets, that is, when any one of the units magnets operates the units off-normal bar is shifted and when any one of the tens magnets operates, the tens off-normal bar is shifted. As indicated in Fig. 4, each off-normal bar when shifted operates a corresponding set of off-normal contacts. The units off-normal contacts are marked E39 and the tens off-normal contacts are marked Ei. The tens and units bars themselves also operate certain off-normal contact sets, for example, any one of the units bars when shifted operates off-normal contacts |32 and any one of the tens bars when shifted operates off-normal contacts |33. The operation of all of these off-normal contacts is accomplished by projections on the bars extending through the channel plate l I2 and these projections engage special operating springs for the off-normal contacts when the bars are shifted. There is also another set of off-normal contacts |35 that may be operated in a similar manner by the latch plate i261. All of these off-normal contacts are indicated particularly in Figs. 1 and 4. The channel plates and |12 may be provided with controlling screws |35 to locate the code and operating bars in normal position and to control the distance through which the bars may be shifted. Various other minor details of the constructionl of the switch will become apparent in connection with the following description of the operation of the switch.

In establishing a connection from one line to another, a particular set of select springs may be selected and operated. To choose such a set of select springs, the operation of the switch would begin by actuating a corresponding combination of tens and units magnets. These magnets actuate the armatures |28 so that the projections |21 will shift corresponding units bars |29, and tens bars I2| and the corresponding off-normal bars |22 and |23 towards the right looking at Fig. 1 or if Fig. 11 is considered towards the left. The shifting of these tens and units code bars will then align a certain series of slots in these bars in preparation for the entry of an extension ||6 for the subsequent operation of the corresponding set of select springs. It will be noted that the corresponding off-normal springs |32 for the units bars and the offnormal springs |33 for the tens bars are operated as well as the off-normal springs |32 operated by the units off-normal bar |23 and the off-normal springs |31 operated by the tens 01T- normal bar 22. The circuit arrangement is such that the operation of the oH-normal contacts |3 and |3| will energize the operating magnets |01 and |08. One of these magnets is shown in perspective in Fig. 10 for example. The

operation of these magnets |01 and |08 will attract their plungers |35. Each of the plungers |36 is attached through an extension |31 to a cam member |38 having an extension |39 surrounded by a control spring |40 to return it :and the plunger |36 to normal when the magnet is deenergized. The cam members |38 are thereby lifted and in being lifted, they permit levers |4| and |42 through associated rollers to be moved towards each other. These members |4| and |42 are connected, respectively, to cross-bars |43 and |44 that extend the whole distance across and on the inside of the various extensions ||E and normally engage these extensions H6. The levers |42 and |4| are permitted to move toward each other by the tension of the operating springs ||5 attached to the extensions ||0 and small springs |49 which may be attached t0 the levers. A particular extension ||6 is thereby permitted to enter the aligned slots on the shifted code bars and thus causes the operation of the associated set of select springs. It will be observed that these levers |4| and |42 have extensions such as |45 and |46. respectively, see Figs. 5, l() and ll, which are located in openings |41 and |48 as shown in the latch plate |24 and as these extensions move toward each other, they release the latch bar |24 as openings |41 and |48 are shaped t permit such release. The latch bar |24 is thereby shifted towards the left as shown in Fig. 1l or if Fig. 1 is considered moved towards the right under tension of spring |50, attached at one end to channel plate ||2 and at the other end to a pin attached to the latch plate |24. These slots |41 and |48 are duplicated at both ends of the latch plate for extensions |45 and |46 of the levers |4| and |42 controlled by the corresponding operating magnets |01 and |03 so that the cross-bars |43 and |44 are now latched or locked in operated position so that the operating magnets |01 and |08 may be released. The extension |S that has entered slots in the actuated code bars holds these code bars in operated positions so that the tens and units magnets operated will also be permitted to release. The switch now remains in this condition which is shown in the cross section Fig. 8 with the selected select springs operated by the associated operating spring ||5 and with the extension ||0 entered into slots in all of the code bars.

When the switch is to be released, the release magnet ||0 is operated. This release magnet is shown particularly in Figs. 1 and 7 and is of the solenoid type provided with the plunger |52 connected to an extension |53 on which is connected a bar surrounded by a restoring spring |54. Core |52 is also provided with a cam member |55 at its lower end which, when the plunger |52 is lifted, will engage a roller |56 on the latch bar |24 and shift the latch bar back to normal and thus cause the release of the cross-bars' |43 and |44 and the associated levers |4| and |42 to normal position. In the returning of the cross-bars |43 and |44 to normal, it is evident that one of them will engage the extension engaged in slots of operated code bars and return it and the associated operating springs ||5 and the select springs to normal and thus permit the operated code bars to return to normal. The release magnet ||0 may now be released and the switch is then fully restored t0 normal.

As stated some of the groups of select springs may be assigned for establishing connections to trunks and when a trunk connection is desired,

the switch may be designed to operate in somewhat dilerent manner from the operation employed in establishing connections to lines. In this case a particular trunk group may be selected and then a connection is established to the iirst idle one of the trunks in this group. To this end tens magnets are'operated in a certain combination to choose the group desired. These special sets ci select springs are located at the right-hand end of the switch, looking at Fig. l or at the left looking at Fig. 11, as indicated at |5 and one of these is selected by the tens code bars to initiate the trunk selection in a particular group of trunks. It is, of course, understood that any of the groups of one hundred select springs may be designated as trunk groups. In this case due to the operation of the tens code hars, the tens oft-normal contacts |33 will operate to cause the operation of the trunk operating magnet S09. This magnet is similiar to the magnets |91 and |08 and operates two levers such as |4| and |42 to release cross-bars similar to cross-bars |43 and |44. One of these is marked |53 in Fig. 1 while the companion bar is not shown but is located on the opposite side from the cross-bar |59. These bars operate in the same manner as the cross-bars |43 and |44 located on the opposite sides of the switch. Either of these bars will release a special set of select springs and establish a corresponding connection. Two sets of these special springs are shown at 200 and 250 in detail in Fig. 13. If, therefore, one of these special sets of springs is selected, it will establish circuit changes in a manner as will be described hereinafter in detail in connection with the circuits shown in Figs. l2 and 13. Sufcient to say at this time is that these special springs will connect the units magnets through a circuit to contacts of a busy relay indicated in Fig. 13 by numeral 20| to establish circuit connections in accordance with a certain code identifying the rst trunk in the selected group and that these circuit connections will cause the operation of a particular combination of units magnets. These units magnets will align slots to permit the selection of a rst set of select springs representing the rst trunk in the group of ten trunks previously selected by the special set of select springs operated and on the operation of these units magnets and their associated oit-normal contacts |32, the operating magnets |01 and |08 will operate as hereinbefore described to permit the select springs of the rst trunk in this group of trunks to establish a connection to the first Trunk, the latch plate |24 will, of course, lock the levers |4| and |42 and the cross-bars |43 and |44 in actuated position and hold the established connection so that the operated magnets w1, |48 and |43 may be released as well as the operated tens and units magnets. In case, however, the first trunk is busy, the busy relay 20| would have been operated at this time so that the leads from the units magnets would have extended through contacts of this relay to a busy relay indicated by numeral 252 in Fig. 13 representing the second trunk in the group and there a connection would have been established from ground for a different code to operate a different combination of units magnets to select the select springs of the second trunk in the selected group of trunks. If this second trunk had been busy, the third trunk would have been selected and so on. When the switch is to be released, the release magnet Will operate in the usual manner to release the switch.

If reference is now made to the Figs. 12 and 13, descriptions will be made to illustrate how these switches may be employed in a telephone system to establish connections between subscribers' lines and between a calling subscriber and an idle trunk in any desired group of trunks leading to a distant olce. In Fig. 12 a switch, such as illustrated in the preceding Figs. 1 to 11, is used as a line finder and has been indicated merely by two sets of select springs as shown at A for one line finder and by two sets of select springs as shown at B for a second line iinder, with the subscribers lines multiplied across from one liner iinder to another. These multiple connections may be arranged as shown for example at |02 in Fig. 1 by conductors arranged in at cable bank formations with the switches arranged side by side. The units magnets for this line finder A have been shown at 206 and the tens magnets at 201, while the units oli-normal contacts |32 operated by the units bar have been shown at 208 and the tens olinormal contacts |33 operated by the tens bars have been shown at 209, and the olf-normal contacts |34 operated by the latch bar |24 have been shown at 2|0. The operate magnets |01 and |38 of the 'line finder A have been indicated by a magnet 233 and the release magnet ||0 by the magnet 24|. This switch used as a line nder is, of course, not equipped with any of the operating parts used in connection with trunking. This line iinder A may be used to extend connections from several groups of subscribers lines of which the subscribers line represents one of the lines from one group while the subscribers line 2|2 represents one of the lines from another group and it should be understood that several other groups of such subscribers lines may terminate in this line finder. These groups of subscribers lines may have access through this line finder to a trunk leading to a selector-connector such as is shown in Fig. 13. -These groups of subscribers lines may also terminate in other line finder switches such as line finder B. The exact circuit operation to accomplish these operations will be described in detail hereinafter in connection with Figs. 12 and 13. If it is assumed that the subscriber of line 2|2 is calling, a circuit is established through his telephone set from battery and ground and the windings of the line relay 2|3, contacts of cut-01T relay 2M, over the loop through the subscribers line 2|2. The operation of relay 2|3 closes a circuit for the operation oi' the relay 2|6 over a connection from battery supplied at an allotter circuit 2H over lead 2|8, the allotter circuit 2|1 being of any well-known type for appropriating the link leading from the line finder A to a selector-connector as shown in Fig. 13 which will be described hereinafter. This relay 2|6 corresponds to the -group of ten lines in which the calling subscribers line 2|2 is located and in operating prevents any other group relay such as 220, for example, from operating if the subscriber in that group would call, as a connection for this particular relay extends through a chain circuit of other group relays over back contacts of each group relay and this connection is broken from the battery supply lead 2|8 on the operation of group relay 2|3. Thus the circuit for group relay 2|6 may be traced from battery on lead 2|8, back contacts of group relay 220 and intermediate relays and relay 2|3, winding of relay 2|6, to ground at contacts of line relay 2|3. Relay 2|6 in operating will close a circuit at its inner right-hand armature and front contact to the battery on lead 2 I8 through the middle armatures and back contacts of other group relays. Group relay 2|| in operating operates a particular tens relay 222, one of which is provided for each group relay, from battery through the winding of this relay, contacts of relay 2|6 to ground, and on the operation of this tens relay a units relay 223 corresponding to the location of the calling subscribers line in the group will be operated over a circuit from the battery on lead 2|3, contacts of units relay 223, corresponding contacts of other intermediate units relays and iinally through contacts of units relay 224 and back through contacts or" the intermediate units relays and contacts of the units relay 223 and its winding, contacts of tens relay 222 to ground at the line relay 2|3. Relay 223, in operating, closes a locking circuit for itself directly to the battery on lead 2| S independent of the connections through contacts of the other units relays.

The allotter 2H, upon receiving a ground circuit from the upper armature of relay 223, now may establish a ground connection over lead 225 for the operation of relay 226 which in operatingr connects the circuits for the tens magnets 201 and units magnets 233 to the tens relays such as 222 and units relays such as 223 and 222 for the operation of va combination of these tens and units magnets in accordance with the ground connections on armatures o1" the operated tens and units relays. The drawings show, for illustration, that only two of the tens magnets and one of the units magnets will operate to establish a connection from calling subscriber 2|2. For example, the tens magnets 22'! and 228 are energized from battery through the windings of these magnets, contacts of relays 226 and 222 to ground and the units magnet 229 is operated from the battery through the windings of these magnets, contacts of relay 226 and of the units relay 223 to ground. It should be understood that, of course, other combination of tens and units magnets may be operated by the operation of corresponding tens and units relays to establish connections from other calling subscribers. It should be observed now that the operating magnet 233V will operate as the oiT-norrnal contacts 208 and 203 controlled by the actuated tens and units bars will close an obvious circuit for this operating magnet 233. This magnet in operating closes as hereinbefore described, the connection through the chosen select springs, in this case marked with the numeral 231i. Thus a connection is established from the calling subscribers line 2|2 through contacts 234 over the link 232. If the allotter has been operated to allot a different line nder and link, a diierent relay corresponding to relay 226 would have operated to connect dierent sets of tens and units magnets of another line finder. In this case the connection might have been established through contacts 233 of line finder B, for example, and the associated link 231.

As a connection is now established from the calling subscriber of line 2| 2 to the link 232 over select contacts 234, a relay in the circuit arrangement marked 23| in Fig. 13 operates over the tip and ring conductors to effect grounding of sleeve conductor 263 to operate the cut-off relay 2M through the left-hand closed contacts of 234. This ground is also returned to the allotter 2|`| through the left-hand contacts of relay 225, causing the operated allotter to be released and to release relay 225. Relay 225 releases the units and tens magnets. The operation of relay 2|4 causes the release of the line relay 2| 3, the group relay 2|5 and the tens and units relays 222 and 223. Grounding of the sleeve conductor also provides a guard condition to prevent a call being routed a busy line, as described hereinafter. With relay 226 released and the orf-normal contacts Zic operated by the operation of the latchfbar, an obvious partial circuit for the release magnet 24| will be established, which circuit will be closed when the connection is no longer desired through the line iinder A as Will hereinafter be described. The operation of off-normal contacts 2|!! also opens the circuit for the operate magnet 233 causing its release.

In Fig. 13, a selector-connector switch has v been illustrated merely by the units magnets 242, tens magnets 243 and the asscoiated units off-normal contacts 244 operated by the units code bars, the tens off-normal contacts 245 operated by the tens code bars and off-normal contacts 246 operated by the latch bar oi this switch as Well as the associated operate magnet 241 controlled by the units off-normal contacts 244 which correspond to magnets l'i and |08 in the switch shown in the structure drawings and the associated operate magnet 24B corresponding to the operate magnet |59 and controlled by the tens bars off-normal contacts 245. D have been shown corresponding to one of the groups of trunks selectable. While these special select contacts 255 may represent a first group of trunks, it should be understood that other special select contacts may represent other trunk groups. One other set of such select contacts has been shown at 255. Associated with each group of trunks there is a trunk-busy relay such as 25| for the first trunk in the rst group and such as relay 252 for another trunk in this rst group. Of the regular select spring contacts in the selector-connector only a few have vbeen shown, for example, for the link 232. The contacts 253 have been shown for connecting the link to the first trunk 254 in the rst group and select contacts 255 for another trunk 255 in this first group for connecting the link 232 to this last-mentioned trunk. rI'here is also shown 4select contacts 253 for connecting the link 232 to an individual line 251. The busy relays 25| and 252, select contacts 253 and 255 and trunks 254 and 255 have been enclosed in a box and` a similar box has been sho-wn to symbolize the busy relay select contacts and trunks for the second group of trunks connectable to link 232. Other circuits for the selector-connector may be indicated, for example, by a box 25| which represents supervisory, pulse and ringing control circuits and by a box 252 representing a counting relay chain or the equivalent -vhich circuits may be of any Well-known type for controlling the establishing of connections in this system. Other parts of the circuits are shown in detail such as the relays 258 and 265 and associated connections. It should be understood that when the link 232 is seized and the supervisory pulse and ringing control circuit is connected, a pulse repeating relay therein Will be operated in series With the subscribers loopy to supply a dial tone In this case a special set of select contacts or similar indication to the calling subscriber that he may begin to dial the desired number. The operation of the last-mentioned relay will cause ground to be returned over sleeve conductor 253 to maintain cut-oft relay 2|4 operated, as stated above. The dialed number may indicate a connection to an individual line such as 251 and includes a tens digit, a units digit and a ringing digit Whereas in case of a connection to a group of trunks, such as has been indicated, a single digit corresponding thereto may be employed. If it is now assumed then that the calling subscriber on line 2|2 dials the digits to establish a connection to the individual line 25?, the tens digit pulses will be transmitted over the tip and ring conductors from the calling subscribers line over select contacts 234, link 232, contacts of the relay 258 to the supervisory, pulse and ringing control circuit in box 26|. These pulses will be transmitted to the counting relay chain circuit, or its equivalent, in box 252 to cause said chain to reset corresponding to the dialed digit to ground a combination of leads extending through contacts of the transfer relay 259 to operate a corresponding combination of tens magnets in the group 243. As soon as one or more of the tens magnets operate, the tens bar oir-normal contacts 245 Will operate as usual and a circuit from battery, Winding of operate magnet 22S, contacts 245 and 246, contacts of relay 258 to a ground in box 252 will be completed to cause the operation of operate magnet 248. This operate magnet corresponds to operate magnet |259 in the switch and consequently will operate the special levers in the switch and cause an extension H5 for a special operate spring H5 to be operated to enter slots in the shifted tens bars and thus lock these bars in operate positions. This operate spring |55 need not in this case control any select springs but is merely employed for locking the tens bars. When the tens bars have been selected and locked, transfer relay 259 will operate due to the operation of off-normal contact 225. The circuit for this relay 269 extends from ground at the contacts 225, Winding of relay 269 to battery in the circuits 252, said battery being withheld until the ground connections to armatures of relay 25s have been removed. Relay 259 in operating, prepares the connections for the units magnets 242 so that when the subscriber now dials the units digit, a corresponding combination of units magnets in group 242 Will be operated. This in turn closes the off-normal contact 244 and a circuit is completed for the operate magnet 241 from battery through the winding oi' this' magnet, the off-normal contacts 244, and the latch plate off-normal contacts to ground, This operation or tens and units magnets and the operated magnets 261 will, as hereinbefore described cause a connection to be established through a corresponding set of select springs such as, for example, 253 to connect the line 251 to the circuit indicated by 25S and as the latch plate |24 immediately thereafter operates the ofi-normal contacts 245, the operate magnets 241 and 243 Will release. If the called line is busy, circuit 25| will receive ground from the sleeve conductor thereof through the bottom contact of relay 258, to result in circuit 25| causing busy tone to be returned to the calling subscriber and to make itself and circuit 252 unresponding to further dialing pulses. The subscriber, in the event the line is idle, may

now dial the ringing code into the circuit 26| and this in turn causes the ringing code or ringing signal to be transmitted from this circuit 26| over the upper armatures and back contacts of relay 268 over the tip and ring conductors and the select contacts 268 and line 251 to the called subscribers station to ring the subscriber. When the called subscriber answers, a tripping relay in circuit 26| operates.

to discontinue ringing current transmission and places circuit 26| in talking condition whereby talking battery is supplied to both subscribers and a suitable transmission path is provided. Circuit 26| may be arranged to have the link held under control of the calling party, the called party, or either, as appropriate. The units magnets 242 that have been operated will have been released by circuit 26| in response to ground received from the right-hand spring of 246, closed by the latch plate operating, while the tens magnets operated in the group 243 were released prior to the operation of relay 269, the connection being held by the latch plate |24. The connection is now established between the subscribers and conversation may begin. When the conversation ends and the appropriate supervisory relay or relays of circuit 26| are released, the busy ground supplied over the sleeve through the bottom back contact of relay 268 and the select contacts 258 on the one hand, and to the calling line over conductor 263, on the other hand, is removed by circuit 26| to cause the cut-orf relays 2| 4 of both lines to be released. Ground is applied over lead 212 by circuit 26| for the operation of the release Y magnet 213 through the off-normal ccntacts246 and for the operation of the release magnet 24| of the line iinder over contacts of relay 22|:` and oir-normal contacts 2li), and these two release magnets restore the selector-connector and the line finder A to normal.

In case the calling subscriber had desired a trunk connection outgoing to a distant cnice, he would have sent a digit representing the tens selection and thereby cause the operation of a certain combination of the tens magnets in the same manner as hereinbefore described in connection with the establishing of a connection to an individual line. The operation of these magnets would, of course, have operated the off-normal contacts 265 and this in turn would have closed a circuit for the operate magnet 248 from battery through the winding of this magnet, contact 245, contacts 246, to ground at the circuit 26| and also the operation of the tens magnets would operate one of the set of contacts at the group as controlled by the tens bars as shown at |25 in Fig. l1. Ii these contacts has been the contacts 206, which would represent the first group of trunks outgoing from this oice, the results would have been as follows: When these contacts are operated and if the first trunk in the group is idle as indicated by the busy relay 26| being released, a particular code connection would be established at the points 215 for operating a corresponding combination of units magnets of the group 242 from battery through the windings of these magnets, over the leads through contacts 200 and contacts of relay 26| to ground as determined by the code connection at 215. 'Ihe operation of these magnets would have then, of course, operated the off-normal contacts 244. 'Ihe operate magnet 241 would be actuated from battery, winding of this magnet, contacts 244,

contacts 246 to ground and thereby cause operation of select contacts in the switch as determined by the operated tens magnets and the units magnets in the same manner as in establishing connections to an individual line. These select contacts are shown as contacts 253 and establish a connection to the first trunk 254 for link 232. The operation of the contacts 266 also closes a circuit for the operation of the relay 268l to close the connection to this link 232 at the upper armatures and front contacts of this relay. This circuit may be traced from a battery in the circuit 26|, lead 21|, upper winding of relay 268, contacts 244, contacts 266 to ground. The operated tens magnet and units magnets in the groups 242 and 243 will release as well as the operate magnets 248 and 241 Whereas the latch plate will hold the established connection for the select contacts 253 and the latch plate will operate the olf-normal contacts 246 to prepare circuits for the release magnet 213. When the connection is established through contacts 253, a circuit for the busy relay 28| will be established from battery, winding of this relay and contacts 253 to ground to make this trunk busy.

It will be recognized that with relay 268 operated, the tip and ring conductors of the calling line will be connected through the line finder and selector-connector to the trunk, clear of any bridged relays. It is contemplated, therefore, that the trunk circuit connected to 254 will be provided with appropriate relays, not shown, to furnish talking battery and to connect ground to the sleeve conductor of the link through contacts 253, said ground being extended to circuit 26| through the bottom front contact of relay 268. This provides holding ground for circuit 26| to cause it to withhold the release condition as long as this ground is maintained, and to cause ground to be extended over conductor 263 to maintain cut-01T relay 2|4 operated and the line nder busy to prevent reassignment by the allotter. When conversation ends and ground is removed from the sleeve conductor at 254, circuit 26| will cause the ground circuit for conductor 263 to be opened and release ground to be extended over conductor 212. Relay 268, together with the line finder and selector-connector, will be released with all apparatus restored to normal and made available to handle another call.

In case this rst trunk has been busy in another connection, the next idle trunk would have been chosen on the operation of the contacts 260, due to the fact that relay 28| is operated. In this case the code combination at 215 would have been disconnected and the connection at the contacts 260 would have been extended through contacts of the next trunk busy relay 252 and if this trunk is idle, the code at the contacts of this relay 252 at 216 would operate a different combination of units magnets. In this case the units magnet would select the select contacts 255 to establish a connection between the link 232 to the second trunk 256. If, on the other hand, the second trunk had been busy, the busy relay 252 would have been operated and the connection from contacts 286 would have been extended to a similar relay for the third trunk and a diierent code in turn would have been applied for the operation of units magnets to establish a connection to the third trunk. It should be understood that the code leads to ground at points such as 215 or 216 may be arranged or changed in any order desired and needv not follow any particular arrangement of the select springs in the switch. It will therefore be seen that this selector-connector arrangement may be employed to establish a connection to an idle trunk without testing the busy trunks individually as the busy relays would be operated so as to establish immediately a connection for the code to select the next idle trunk. Trunk-busy relays may be provided common to a plurality of selector-connectors.

Ii all trunks in the group are busy, indications will be given to circuit 26| so that it may by suitable means cause a busy tone to be returned to the calling party. To this end the bottom contacts of all trunk-busy relays, such as 20| and 252, are arranged in a series chain circuit to ground supplied at the front contact of the last busy relay of the trunk group. Therefore, if all of these relays are operated indicating that no idle trunks are available in the group, this ground will be extended to the left-hand contacts of 290 and if the contacts 260 are then operated in an attempt to extend a call to this trunk group, ground will be extended to circuit 26| to cause it to furnish the busy signal to the calling subscriber.

It will be understood that the switching mechanism which has been described as operating as a line nder and selector-connector may also be adapted to serve as a selector, in which case all of the bank contacts such as 253 will extend to trunks and none to subscribers lines, or adapted to serve as a regular connector in which case all contacts such as 253 will extend to subscribers lines and the trunk hunting feature including relays 265, 252 and contacts 20S and 250 may be omitted, or as a rotary connector, in which case the arrangements will be substantially as shown by Fig. 13, except cut-through relay 268 may be omitted inasmuch as it will be desirable for talking battery and supervision to be supplied by circuit 26|. It will be understood that other applications ci the switching mechanism may be made within the spirit and scope of the invention as shown by the drawings and set out above.

In practicing this invention, the wiring shown connected to terminals |02 may be arranged in the form of a bank of such length that a plurality of switches may be connected thereto. Such bank wiring is indicated in section in Fig. 1, and Figs. 5 and 8 show the connections of select springs thereto. As many switches such as line nders, selectors, connectors, or selector-connectors may be mounted on one bank as required to serve the traffic to or from the connected lines, trunks or combination thereof as appropriate. All of the switches on a given bank need not be of the same type inasmuch as line nders and connectors for a particular one hundred lines may be mounted together. Where selector-connectors are employed, these may be connected to the same bank as the line finders for the corresponding lines, in which case one or more tens of the bank wiring may be employed for trunks.

The switch disclosed may be employed in various switching systems where selection is required. Contact springs I i4 are indicated as being oi the circuit closing, or make, type. It is apparent that each group of springs I4 may be oi other types, such as break, transfer or continuity, as appropriate for the circuit use of the switch.

What is claimed is:

l. A switching device comprising a primary and a secondary set of iiat longitudinally movable bars each provided with notches along its opposite edges, an incoming line, a plurality of outgoing lines, contacts for connecting the incoming line to any one of the outgoing lines, means for longitudinally moving bars in the primary set in combination to select a corresponding group of contacts from which a subsequent choice may be made to establish a connection, means thereafter operative in response to the longitudinal movement of said primary set of bars in combination for actuating a combination of bars in the secondary set, and means for actuating a set of contacts in the selected group of contacts corresponding to the combination of moved bars in the secondary group of bars to close a connection between the incoming line and a corresponding outgoing line, said means for selecting and actuating a set of contacts including means cooperating with the notches of both Sets of bars.

2. A switching device comprising two sets of code bars, an incoming line, a plurality of outgoing lines, contacts for connecting the incoming line with any one of the outgoing lines, another group of contact sets, means for actuating one set of code bars in combination to select a group of said first-mentioned contacts from which the subsequent selection may be made and for actuating one of the sets of contacts in said second-mentioned group, means operative in response to said actuated set of contacts in said second-mentioned group being operated for actuating said second set of code bars in a predetermined combination to select and actuate the corresponding set of contacts in the selected group for connecting the incoming line to a particular idle outgoing line.

3. In a switching system, an incoming line, a plurality of outgoing lines, a switch comprising a primary and a secondary set of flat bars, each with opposing rows of notches arranged in accordance with a code, a magnet for each bar adapted to longitudinally move its associated bar, sets of contacts controlled by the notches of said bars when actuated by said magnets for connecting the incoming line to any one of the outgoing lines, means whereby the actuation of combinations of said magnets to actuate the corplurality of outgoing lines, a switch comprising a primary and a secondary set of flat and relatively long bars, each with notches arranged in accordance with a code along its opposing edges, a magnet for each bar adapted to longitudinally move its associated bars, sets of contacts for connecting the incoming line with any one of the outgoing lines and controlled by the notches of said bars when the bars are actuated by said magnets, means whereby the actuation of combinations of said magnets to actuate corresponding bars in the primary set causes the selection of a group of said sets of contacts for subsequent operation, means responsive to the operation of said bars in the primary set for transmitting code signals to the magnets for the secondary set of bars to operate latter said magnets and bars accordingly to actuate a correspondving set of contacts insaid selected group for establishing a connection between the incoming line and the corresponding outgoing line, said means to select and actuate a selected set of contacts including means cooperating with the notches of both sets of bars.

5. In a switching system, an incoming line, a plurality of outgoing lines, a switch comprising a primary and a. secondary set of longitudinally movable relatively long :dat bars each provided with two opposing rows of notches arranged in accordance with a code, a magnet for each bar, sets of contacts for connecting the incoming line with any one of the outgoing lines and controlled by the notches of said bars when the bars are actuated by said magnets, means whereby the actuation of a combination of said magnets to actuate corresponding bars in the primary set causes the selection of a group of said sets of contacts for subsequent operation, means responsive to the operation of said bars in the primary set for transmitting code signals to the magnets for the secondary set of bars to operate latter said magnets and bars accordingly to actuate a corresponding set of contacts in said selected group for establishing a connection between the incoming line and the corresponding outgoing line, and means for controlling said code signals to select a predetermined idle one of the outgoing lines in the selected group for connection to the incoming line.

6. In a switching system, an incoming line, a plurality of outgoing lines, a switch comprising a primary and a secondary set of bars adapted for longitudinal movement, each bar consisting of a thin flat strip of a length in excess of ten times its width and provided with two longitudinal rows of notches arranged in accordance with a code, a magnet for each bar, sets of contacts controlled by the notches of said bars when actuated by said magnets for connecting the incoming line with any one of the outgoing lines, means whereby the actuation of combinations of magnets to actuate corresponding bars in the primary set causes the selection of a group of said sets of contacts for subsequent operation, means responsive to the operation of said bars in the primary set for transmitting code signals to the magnets for the secondary set of bars to operate latter said magnets and bars accordingly to actuate a corresponding set of contacts in said selected group for establishing a connection between the incoming line and the corresponding outgoing line, and means for controlling said code signals to cause the selection of an idle one of the outgoing lines in the selected group for connection to the incoming line, last said means being operative when a preceding outgoing line becomes busy.

'7. In a switching system, a substantially at bank of conductors, a plurality of switches provided on, and extending across, said bank, circuit conducting means individual to each switch, selective means in each switch operable in particular combinations to select particular bank conductors corresponding `to each said combination, means in each switch responsive to each operation of said selective means for interconnecting the bank conductor so selected with the circuit conducting means corresponding to said switch and means for operating said selective means of said switches whereby any circuit conducting means may be interconnected with any bank conductor.

- 8. In a switching system, a substantially ilat bank of conductors, a plurality of circuit conducting means distributed along said bank, contact actuators arranged in pairs of parallel rows transverse to said conductors with each pair of rows corresponding to one of said circuit conducting means, a pair of contacts closeable by each contact actuator, with one contact of each pair connected to a bank conductor and the other contact of each pair connected in multiple to the circuit conducting means corresponding to the pair of rows in which said second-mentioned contact is located, a group of movable code bars located between each pair of rows of actuators, means to move the code bars in each group in particular combinations to select said contact actuators individually corresponding to each of said combinations and means individual to each group of code bars operable after a particular combination of code bars has been moved to effect the operation of the contact actuator thus selected whereby any of said bank conductors may beinterconnected with any circuit conducting means.

9. In a switching system, a plurality of circuit closing means arranged in two parallel rows, code bars provided between said rows of circuit closing means, means to displace said code bars longitudinally in various combinations, each combination corresponding to a particular circuit closing means and means cooperating with said code bars to eiect the operation of a particular circuit closing means predetermined by the displacement of a corresponding combination of code bars.

l0. A switching device including two parallel rows of contact groups, an actuator for each contact group normally sprung to tend to operate its associated contact group, retention means interposed between the two rows of actuators to normally prevent said actuators from operating their contacts, a plurality of movable code bars interposed between said rows of actuators, each bar having recessions adapted upon movement of said code bars in particular combinations to be aligned opposite said actuators with each particular combination resulting in alignment of recessions opposite a corresponding particular one of said actuators, means to move said code bars in any of said combinations and means operative subsequent to said movement of the code bars to withdraw said retention means to permit all of said actuators to attempt to operate their associated contact group but all but a particular one being prevented from so doing by said code bars, said particular one operating its A contact group by virtue of the alignment of the having notches on both sides of said bars arsaid code bars corresponding Vranged in accordance with a code, a calling line incoming to said switch, lines arranged in groups outgoing from said switch, means responsive to impulses received over the incoming line for longitudinally moving a set of said bars to select a group of outgoing lines, means responsive to said selection for longitudinally moving other of said bars to select an idle line in the selected group and means for interconnecting the incoming line with the selected idle outgoing line, last said means including means cooperating with the notches on said bars.

12. In a switching system, a switch including code bars, a calling line incoming to said switch,

lines arranged in groups outgoing from said switch, means responsive to impulses received over said incoming line for actuating a. set of code bars, a set of contacts operated in response to the operation of said code bars for selecting a group of outgoing lines corresponding to the impulses received, and means responsive to the operation of said contacts for operating said switch to actuate another set of code bars representing a preselected idle line in the selected group and contacts controlled jointly by said two sets of operated code bars for connecting the calling line directly to said preselected idle line in the selected group.

13. A switching device comprising a primary and a secondary set of code bars, an operating magnet for each code bar, an incoming line, a plurality of groups of outgoing lines, a primary group of contacts for connecting the incoming line with any one of the outgoing lines, a secondary group of sets of contacts in operative relationship to said primary set of code bars with each secondary contact set corresponding to a group of outgoing lines, means to maintain on contacts of each set of secondary contact sets a code condition representing an idle line in the corresponding group of outgoing lines, means for energizing magnets for actuating in combination code bars in the primary set of code bars to select a group of rst-mentioned contacts from which a subsequent selection is to be made and to select the corresponding set of contacts in the secondary group, means to actuate the selected set of contacts in the secondary group, means to energize magnets in response to the code condition on contacts of the actuated secondary set of contacts to operate the code bars in the secondary set of code bars in combination whereby the contacts in the primary group corresponding to an idle outgoing line in the selected group is selected, and means to actuate the latter selected contacts to interconnect the incoming line with the outgoing line corresponding to last mentioned contacts.

JUDSON OD SHEPHERD. 

